gcvT

Gene Description

gcvT encodes aminomethyltransferase (EC 2.1.2.10), also known as glycine cleavage system T protein, which catalyzes the final step of the glycine cleavage system: the transfer of the aminomethyl group from the lipoyl-bound intermediate (on gcvH) to tetrahydrofolate (THF), producing 5,10-methylene-THF and releasing ammonia. The enzyme belongs to the GcvT family and functions as a component of the glycine cleavage complex, working in concert with gcvP (P protein, glycine dehydrogenase), gcvH (H protein, lipoyl-carrier), and gcvL (L protein, dihydrolipoyl dehydrogenase). In methylotrophs, the glycine cleavage system connects the serine cycle to the THF one-carbon pool: glycine (produced from serine by serA) is oxidatively cleaved by the GCV system, generating 5,10-methylene-THF (which feeds into C1 metabolism), CO2, and ammonia. GcvT contains two characteristic domains: an aminomethyltransferase folate-binding domain (residues 25-274) and a C-terminal domain (residues 305-385). The enzyme is essential for glycine catabolism and for connecting amino acid metabolism to the THF-dependent one-carbon pool, allowing the organism to recycle one-carbon units between different pathways during methylotrophic growth.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0004047 aminomethyltransferase activity	IEA GO_REF:0000120	ACCEPT	Summary: This is the primary and specific catalytic activity of GcvT - the transfer of the aminomethyl group from the lipoyl-bound intermediate (on gcvH) to tetrahydrofolate, producing 5,10-methylene-THF and ammonia. [file:METEA/gcvT/gcvT-uniprot.txt, "aminomethyltransferase"; "N(6)-[(R)-S(8)-aminomethyldihydrolipoyl]-L-lysyl-[protein] + (6S)-5,6,7,8-tetrahydrofolate = N(6)-[(R)-dihydrolipoyl]-L-lysyl-[protein] + (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + NH4(+)"]. Falcon deep research independently confirms this is the conserved, core catalytic role of GcvT across bacteria and corroborates the products of the reaction. Supporting Evidence: file:METEA/gcvT/gcvT-deep-research-falcon.md transfers the aminomethyl group from the H-protein intermediate to THF, producing 5,10-methylene-THF and releasing NH3 file:METEA/gcvT/gcvT-deep-research-falcon.md is a core catalytic component of the glycine cleavage system
GO:0005960 glycine cleavage complex	IEA GO_REF:0000002	ACCEPT	Summary: GcvT is a component of the glycine cleavage complex, working together with gcvP, gcvH, and gcvL to catalyze the oxidative cleavage of glycine. This is the primary cellular location for the enzyme. [file:METEA/gcvT/gcvT-uniprot.txt, "Glycine cleavage system T protein"]. Falcon deep research confirms GcvT (the T protein) functions with the GCS P, H, and L proteins, with the H protein carrying the lipoyl-bound aminomethyl intermediate that GcvT acts on. Supporting Evidence: file:METEA/gcvT/gcvT-deep-research-falcon.md functions with GCS P, H, and L proteins; H protein carries the lipoyl-bound intermediate
GO:0006546 glycine catabolic process	IEA GO_REF:0000002	ACCEPT	Summary: GcvT catalyzes the final step of glycine catabolism via the glycine cleavage system, transferring the aminomethyl group to THF and releasing ammonia. This connects glycine degradation to the one-carbon pool. [file:METEA/gcvT/gcvT-uniprot.txt, "Glycine cleavage system T protein"]. Falcon deep research corroborates that by producing 5,10-methylene-THF, GcvT links glycine interconversion to the one-carbon folate pool, which in Methylorubrum extorquens AM1 feeds assimilation pathways including the serine cycle. Supporting Evidence: file:METEA/gcvT/gcvT-deep-research-falcon.md By producing 5,10-methylene-THF, GcvT links glycine interconversion to the one-carbon folate pool file:METEA/gcvT/gcvT-deep-research-falcon.md H4F-dependent enzymes help maintain high levels of intermediates needed to feed the assimilatory serine cycle
GO:0008483 transaminase activity	IEA GO_REF:0000043	KEEP AS NON CORE	Summary: This is technically correct as GcvT transfers an aminomethyl group, but it's a somewhat misleading general term. The more specific term GO:0004047 (aminomethyltransferase activity) provides better functional annotation.
GO:0016740 transferase activity	IEA GO_REF:0000043	KEEP AS NON CORE	Summary: This is a very general parent term for all enzymes that transfer functional groups. While technically correct, the more specific term GO:0004047 provides much better functional annotation.

Core Functions

GcvT catalyzes the final step of the glycine cleavage system, transferring the aminomethyl group from the lipoyl-bound intermediate (on gcvH carrier protein) to tetrahydrofolate (THF), producing 5,10-methylene-THF and releasing ammonia. The enzyme functions as a component of the glycine cleavage complex, working in concert with gcvP (P protein), gcvH (H protein), and gcvL (L protein) to catalyze the oxidative cleavage of glycine. In the context of methylotrophic metabolism, the glycine cleavage system connects the serine cycle to the THF one-carbon pool: glycine (produced from serine) is oxidatively cleaved, generating 5,10-methylene-THF that feeds into C1 metabolism, plus CO2 and ammonia. GcvT contains an aminomethyltransferase folate-binding domain and a C-terminal domain, and belongs to the GcvT family. The enzyme is essential for glycine catabolism and for recycling one-carbon units between amino acid metabolism and the THF-dependent one-carbon pool during methylotrophic growth.

Molecular Function:

aminomethyltransferase activity

Directly Involved In:

glycine catabolic process

In Complex:

glycine cleavage complex

Supporting Evidence:

file:METEA/gcvT/gcvT-uniprot.txt
aminomethyltransferase...Glycine cleavage system T protein...N(6)-[(R)-S(8)-aminomethyldihydrolipoyl]-L-lysyl-[protein] + (6S)-5,6,7,8-tetrahydrofolate = N(6)-[(R)-dihydrolipoyl]-L-lysyl-[protein] + (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + NH4(+)
file:METEA/gcvT/gcvT-deep-research-falcon.md
transfers the aminomethyl group from the H-protein intermediate to **THF**, producing **5,10-methylene-THF** and releasing **NH3**
file:METEA/gcvT/gcvT-deep-research-falcon.md
By producing **5,10-methylene-THF**, GcvT links glycine interconversion to the **one-carbon folate pool**
file:METEA/gcvT/gcvT-deep-research-falcon.md
functions with GCS **P, H, and L** proteins; H protein carries the lipoyl-bound intermediate

Gene Description

Existing Annotations Review

Core Functions

References

Deep Research

Falcon

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